1. Field of the Invention
The present invention relates to a vehicle composed of a running mechanism having a running motor and a lifting mechanism having a lifting motor. More particularly, the present invention relates to a vehicle which can change a control system of a lifting mechanism.
2. Description of the Related Art
An electric vehicle is used in a work area in a factory. An electric type forklift truck is used as the electric vehicle, for example. The forklift truck, hereinafter referred to simply as a xe2x80x9cforkliftxe2x80x9d, is composed of a running mechanism and a lifting mechanism. The running mechanism is composed of a running motor as a driving source for running of the forklift, an accelerating mechanism and a braking mechanism. The lifting mechanism is composed of a lifting motor as a driving source for a lifting operation by the forklift, an operation lever, and a hydraulic pressure mechanism.
The running control circuit carries out the control of the running motor. The lifting control circuit carries out the control of the lifting motor.
The lifting control circuit is classified based on a driving system of the lifting motor. The types of driving system of the lifting motor may be classified into a manual lever contactor system, a manual lever chopper system and a joystick chopper system.
The lifting control circuit of the manual lever contactor system monitors a switch in conjunction with the movement of an operation lever operated by an operator of the forklift. The lifting control circuit drives the lifting motor in accordance with the turning on or turning off of the switch. The lifting control circuit of the contactor system realizes the control of only the two states, start and stop of the lifting motor.
The lifting control circuit of the chopper system monitors a chopper which carries out voltage control in conjunction with the movement of an operation lever operated by an operation person of the forklift. The lifting control circuit drives the lifting motor in accordance with the voltage value outputted from the chopper. The lifting control circuit of the chopper system can realize multistage speed control of the lifting motor. The chopper system is classified into a simple chopper system and a complex chopper system in accordance with the number of stages of the settable output voltage. In the simple chopper system, two or three stages of output voltage can be set and correspond to lifting speed. In the complex chopper system, three or more stages of the output voltage can be set.
In the lifting control circuit of a joystick system, a lifting motor is driven in accordance with the movement of a single operation lever operated by the operator of the forklift. In the joystick system, the chopper voltage is adjusted to allow the continuous control of the lifting motor to be realized.
The contactor system and simple chopper system are mainly used in the U.S. The complex chopper system and joystick system are used in Europe and Japan.
The running control circuit has the same specification, even if the specifications of the lifting control circuit are different from each other.
FIG. 1 shows a block diagram of a conventional forklift. Referring to FIG. 1, the forklift 10 is composed of a control substrate 11, a running motor 12 and a lifting motor 13. The control substrate 11 is composed of a running control unit 11a and a lifting control unit 11b. The control substrate 11 may be further composed of a joystick control unit 11c in accordance with the specification of the lifting control.
The running control unit 11a carries out torque control of the running motor 12. The running motor 12 realizes the running of the forklift 10. The lifting control unit 11b detects the movement of a plurality of operation levers to control the lifting motor 13, when the specification of the lifting operation is the contactor system or the chopper system.
The joystick control unit 11c detects the movement of the joystick to instruct the lifting control unit 11b to drive the lifting motor 13 in accordance with the detection result, when the specification of the lifting operation is the joystick system.
In case that the specification of the lifting operation is a relatively simple contactor system and a simple chopper system, the running control unit 11a can carry out the process to be carried out by the lifting control unit 11b in place of the lifting control unit 11b. In case that the specification of the lifting operation is the contactor system or the simple chopper system, the control substrate 11 is installed with the running control unit 11a and/or the lifting control unit 11b. In case that the specification of the lifting operation is the complex chopper system, the running control unit 11a and the lifting control unit 11b are installed on the control substrate 11. When the specification of the lifting operation is a joystick system, the joystick control unit 11c is installed on the control substrate 11 in addition to the running control unit 11a and the lifting control unit 11b. 
In the conventional forklift, the running control unit (circuit) 11a, the lifting control unit (circuit) 11b and the joystick control unit (circuit) 11c are installed onto the single substrate 11. Therefore, when of the substrate is selected in accordance with the specification, the assembly of the running control and the lifting control is manufactured.
However, the substrate is prepared in accordance with the specification to have the running control unit 11a and the lifting control unit 11b (joystick control unit 11c). Therefore, the reduction of substrate cost through the mass production is difficult, even if the running control circuits are identical to each other. Also, when a fault occurs in either of the running control circuit and the lifting control circuit, the normal circuit is also replaced at the same time. Therefore, the reduction of maintenance cost is difficult.
Therefore, an object of the present invention is to provide a vehicle in which a running control structure and a lifting control structure are separated.
Another object of the present invention is to provide a vehicle in which the substrate cost can be reduced through mass production effect of the running control structure.
Still another object of the present invention is to provide a vehicle in which the reduction of maintenance cost can be realized when any fault occurs in either of the running control structure and the lifting control structure.
In order to achieve an aspect of the present invention, a vehicle includes a running mechanism, a work mechanism, a master unit, a slave unit, and a communication interface. The running mechanism is used for running of the vehicle, and the work mechanism is used for a work by the vehicle. The master unit controls the running mechanism, and the slave unit controls the lifting mechanism. The communication interface carries out establishment and release of electric connection between the master unit and the slave unit.
The slave unit may include a function storage unit, a work control unit and a function notifying unit. The work control unit stores data indicative of a control system of the work mechanism in the function storage unit. The function notifying unit reads out the control system data from the function storage unit to notify the master unit through the communication interface. In this case, the master unit may include a partner checking unit for issuing a function notify request to send to the slave unit through the communication interface. The function notifying unit responds to the function notify request to read out the control system data from the function storage unit to notify the master unit through the communication interface.
Also, the partner checking unit issues the function notify request in response to the start of the vehicle or change of a mode from a stop mode to an operation mode. In this case, the master unit includes a running control unit for controlling the running mechanism, and monitors an operation of the vehicle and changes the mode from the operation mode to the stop mode, when the vehicle is not driven for a predetermined time.
Also, the master unit may include a running control unit which controls the running mechanism, and a partner setting unit which instructs the running control unit to start control of the work mechanism through the communication interface, when the partner checking unit cannot receive the control system data from the slave unit through the communication interface.
Also, the work control unit starts control of the work mechanism based on the control system of the work mechanism in response to a control instruction from the master unit through the communication interface, when the master unit issues the control instruction. In this case, the master unit may include a partner setting unit which issues the control instruction to the slave unit through the communication interface, when the control system data is received from the slave unit through the communication interface.
Also, when the vehicle is a forklift and the work mechanism is a lifting mechanism, the work mechanism has a work motor, and the work control unit controls the work motor in response to an operation instruction. In this case, the slave unit may have an instruction lever for instructing an operation of the lifting motor, and for generating the operation instruction in response to an operation of the instruction lever. Instead, when the slave unit may have a joystick for instructing an operation of the lifting motor, and for generating the operation instruction in response to an operation of the joystick.
Also, the lifting motor may be instructed to carry out a constant speed operation, a multi-stage variable speed operation, or a continuously variable speed operation.
In the above, it is desirable that the master unit and the slave unit are assembled on different substrates, respectively.
In order to achieve another aspect of the present invention, a vehicle includes a running mechanism used for running of said vehicle, a working mechanism used for a work by said vehicle, a slave unit provided on a second substrate to control said working mechanism in response to an instruction, and a master unit provided on a first substrate to control said running mechanism and to selectively said working mechanism based on a function of said working mechanism.
Also, in a still another aspect of the present invention, a method of controlling a working mechanism, is attained by setting a control system of a working mechanism; by communicating between a running controller and a working controller such that a running controller recognizes said control system of said working mechanism; by controlling a running mechanism by said running controller; and by selectively controlling said working mechanism by said running controller or said working controller based on establishment of the communication and said control system of said working mechanism.